A light emitting diode (LED) is a kind of semiconductor device that converts electricity into light for example infrared light, which is used as a light source, for signal transmission and reception, using the characteristics of a compound semiconductor.
A group III-V nitride semiconductor has been widely used as a core material for light emitting devices, such as light emitting diodes (LEDs) or laser diodes (LDs), thanks to the physical and chemical properties thereof.
LEDs do not contain any material that causes environmental pollution, such as mercury (Hg), which is used in conventional lighting apparatuses such as incandescent lamps and fluorescent lamps. Consequently, LEDs exhibit excellent environment-friendly characteristics. In addition, LEDs are characterized by a long lifespan and low power consumption. For these reasons, LEDs have replaced conventional light sources.
In a conventional light emitting device package including a light emitting device and a lens located on the light emitting device, the upper edge of the lens is dark, whereby illuminance on a target illuminance surface is non-uniform.